Carburetor for internal combustion engines



Aug. 9, 1932. P. L. LEMOINE CARBURETOR FOR INTERNAL COMBUSTION ENGINES Filed Dec. 19, 1930 s Sheds-Sheet 1 3 a a a N INVENTOR 2 w PAUL LOUIS LEMOINE WMvCL,

ATTQRNE-YS Aug. 9, 1932. P. LEMOINE 1,370,578

CARBURETOR FOR INTERNAL COMBUSTI'Q N ENGINES File Dec. 19, 1930 3Sheecs-Sheet 2 fikiomy Aug. 9, 1932. P. L. LEMOINE CARBURETOR FOR INTERNAL COMBUSTION ENGINES F-iled Dec. l9, 1930 5 Sheets-Sheet 3 par Patented Aug. 9, 1932 UNITED STATES PATENT OFFICE PAUL LOUIS LEMOINE, F PARIS, FRANCE Application filed December 19, 1930, Serial No. 503,443, and in France January 7, 1930.

The present invention relates to improvements in acarburetor, the principle of which is already known, and which comprises a float chamber, a jet situated in the mixing chamber at the end of the fuel pipe coming starting in the passage chamber (between the the carburetted air.

valve and the mixing chamber) and opening into the upper part of the float chamber above the level of the fuel, the said float chamber being air-tight to atmosphere; a duct starting at the atmosphere and terminating in the mixing chamber close to the extremity of the fuel jet, the axis of the extremity of the duct and the axis of the jet being approximately or exactly perpendicular one to the other, and arranged in such manner that a jet of air leaving the duct meets the extremity of the jet.

Carburetors of this type have numerous advantages but they have the following defeet. When the speed of the motor increases from its lowest speed, the supply of fuel becomes insufficient from the moment when the valve lifts. This shortage of fuel then decreases when the speed increases more, and the supply becomes correct at the high speeds, for which the area of the jet has been selected.

.The invention does away with this defect. It consists in adding to the combination of devices just described, another device consisting in a pipe which connects the upper part of the float chamber with atmosphere, this pipe being provided with a damper controlled by the valve in such manner that it opens when the valve lifts.

The invention comprises, furthermore; let a device increasing momentarily the output of the jet on the sudden opening of the throttle of carburetted air; 2nd a special device of a piston connected with the automatic valve, which suppresses the rapid oscillations of this valve; 3rd a throttle valve constituted in a particular manner so as to obstruct as little as possible the area of the passage for The invention is shown on the drawings attached to the description and in which:

Figure 1 shows in vertical axial section, as an example of a carburetor of the vertical type in accordance with the invention.

Figure 2 is a vertical section on the line 2-2 of Figure 1.

Figure 3 is a vertical section on 3-3 of Figure 1.

Figure 4 is a horizontal section on 4'4= of Figure 1.

Figure 5 is a plan of a carburetor according to that shown by Figures 1, 2, 3 and 4, but in which the cylinder 20 instead of hav ing its axis in the symmetrical plane of the carburetor is removed from this for facility of manufacture of the carburetor, and the mounting of the said cylinder 20.

Figure 6 reproduces, with a variation in the execution, a part of Figure 1.

Figure 7 reproduces with a variation of execution, another part of Figure 1.

The general construction of the carburetor shown in these figures is as follows. The carburetor body 1 is in a single piece comprising the float chamber 2. On this part 1 is fitted on the one hand the cover 126 of the chamber 2, fixed in the example shown by two bolts 127, 128 with a plastic joint 103 interposed, and on the other hand a cylinder 20 in which slides a piston 21 connected with the valve 6 by a screw 85; 7 is the seat of the valve 6; 56 is an adjustable stop of the valve 6. In the example shown the valve 6 is loadedonly by its own weight and that of the parts which are connected with it but it might be loaded with a spring (not shown) 113 is the float situated in the chamber 2; 117 is the part through which the fuel enters and in which slides the needle (not shown), controlled by the float 113 and which regulates the supply of fuel into the chamber 2; 5 is the throttle valve of the carburetted air; 3 (Figure 2) is the jet opening into the mixing chamber 14 at the end of the fuel duct 4 coming from the chamber 2; 11 (Figure 2) is the pipe starting at atmosphere and terminating close to the extremity of the jet 3 by a nozzle 12 situated in such manner that a ct of air coming from it strikes the extremity of the jet 3 and so that the axes of this nozzle 12 and of the 3 are exactly or approximately perpendicular one to the other, so that the air jet leaving the nozzle 12 creates in the jet a depression which draws the fuel from it, and which pulverizes this fuel on its exit, the current of carburetted airis directed to the part left open by the throttle 5 when this is almost closed; the pas sage chamber 10 of the carburetor, between the valve 6 and the mixing chamber 14, communicates with the upper partof the float chamber 2 by the series of ducts 13, 133, 136 and 132. In the example, the body of the carburetor-1 is-closed by a cover 143 which is fixed thereto by bolts 144, a plastic joint '145 being interposed; a hole 18 gives com.-

munication between the two parts 9 and 10 of the carburetor situated respectively before and after the valve 6; this hole 18 is -con trolled by a damper 19 mounted in a part 146 screwed into the cover 143; the aperture of the hole 18 is regulated by screwing the piece 146, but it is possible to completely throttle this hole 18 momentarily for the starting of the motor, by simply pressing on the damper 19, for example through the intermediati on of a lever (not shown).

Keeping to the description just made and I which does not comprise the improvements brought about by the present invention, the action of the carburetor is as follows. The

motor is started, acting if it is necessary by momentary pressure on the throttle 19 as has been stated. The weight of the combination of the valve 6 and of the piston 21 (and eventually the effect of .a spring not shown) keeps the valve 6 on its stop 56 which is regulated in such manner that the valve 6 is very close to itsseat 7 A certain suction is thus created in the carburetor and consequently the pipe 11 (Figure 2) is traversed by a strong current of air which draws the fuel from the jet 3 and pulverizes it on its exit. A second and violent pulverization takes place in the passage left free by the throttle valve 5. The supply of fuel, at the lowest speed ofthe motor, is regulated by the choke 19. The more this choke is closed, the greater is the suction in the carburetor and the stronger is the current of air passing through the pipe 11, and the greater is the supply of fuel.

If the throttle valve 5 is then gradually opened, the speed of the. motor increases and the suction increases inside the carburetor, althoughthis suction is not sufliciently strong to lift the valve 6. Consequently, up to the moment when this valve rises, the current of air which flows through the pipe 11 becomes stronger and stronger, and the supply of fuel. becor'nesgreater and greater and remains sufficient. But from the moment when the speed of the mot/or is sufiicient to cause the valve 6 to lift, the suction inside the carburetor remains constant, and consequently the supply of the jet, under the action of the constant current of air, also remains constant when the speed of the motor increase But the jet 3 is also subjected to another influence which is that of the suction created in the mixing chamber 14 and which corresponds to the speed of the air passing it, that is to say, to the speed of the motor. The supply from the jet thus increases with the speed of the motor like the supply from the jet of an ordinary carburetor. But practically'at thelow speed of the motor at which the valve 6 lifts, the suction corresponding to the speed of the air in the mixing chamber 14 is still negligible. Its effect is therefore insuflicient and there is a shortage of fuel at the motor speeds a little higher than that at which the valve 6 lifts. When the speed increases still more, the effect of the suction in the mixing chamber 14 makes itself felt and the supply of fuel improves. It becomes correct at high speeds of the motor, for which the area of the jet 3 has been arranged. At these high motor speeds, the effect of the jet of air leaving the duct 11 is negligible, and the jet behaves like the jet of an ordinary carburetor, that is to say, that it supplies simply under the action of the suction which corresponds to thespeed of the air in the mixing chamber 14.

The invention which has for its object to overcome the shortage of fuel which has been pointed out, consists in a duct 84, 141, 86, 87 which starts at its extremity 84 at atmosphere, and terminates, by the intermediat-ion of the annular chamber 136 and the conduit 132, at the upper part of the float chamber 2.. This conduit 84, 141, 8 6, 87 is provided with a throttle 85 oontrolled'by the valve 6, and which opens when this valve lifts. In the example, this throttle is simply the screw 85, the lower face of which blocks the upper extremity of the conduit 84 made in the part 56 serving as adjustable stop for the valve 6.

The action of this arrangement is as follows: lVhen the speed of the motor is suiti- "ciently high for the valved to lift, the throttle 85 opens the extremity of the conduit 84 and the float chamber 2 which, until then,

was in communication only with the cham- U ber 10 means of the conduit 13 and of gauged holes 133, is thus placed in communication with atmosphere by the conduit 84, so that the pressure increases in this chamber 2 and the supply from thejet 3 also increases in proportion as the valve lifts and until the conduit 84 is completely opened. The increase of pressure in the chamber 2 depends on the ratio of the areas of the conduit- 141 and the gauged holes 133. In the example, the throttle 85 closes the conduit 84 which has a larger diameter than that of the conduit necessary to completely open the conduit 141.

placed at any point in the conduit to be 141, so that a smaller lift of the valve 6 is throttled. It may, in particular, be a needle of any suitable shape.

The invention also comprises a device which has for its object to remedy the following phenomena. If in a carburetor such as has been described, the throttle valve 5 is suddenly opened, it is found that there is a shortage or fuel for a short time. An example of the arrangement according to the invention which overcomes this difiiculty is shown in Figure 1, and consists in a vertical cylindrical rod 137 capable of sliding in the bore 13 of the part 134. This part- 134 is screwed into the body of the carburetor making a oint with it at 135. At its lower part is screwed a plug 139 bored with a hole 142 which communicates with atmosphere. The head 138 of the rod 137 stops this rod at the top on a shoulder of the piece 134 and at the bottom on the plug 139, the hole 142 of which it blocks up more or less perfectly. The rod 137 thus constitutes a piston movable in a cylinder. Its upper face is subject to the suction in the chamber 10, and its lower face is under atmospheric pressure. The weight of this rod is such that it is not drawn upwards by the suction in the chamber 10 suflicient to raise the valve 6 but by a suction slightly greater.

The action of this arrangement is as follows: On the sudden opening of the throttle valve 5, the valve 6 only rises slowly, as will be hereafter explained. Consequently, for a short time the suction in the chamber 10 is greater than that for which the valve 6 is regulated, and is suflicient to draw upwards the rod 137 which obstructs the holes 133. As soon as the valve 6 has lifted sufficiently, the suction in the chamber 10 is no longer sufiicient to hold the rod 137 which again falls and uncovers afresh the holes 133. During the short time the holes 133 have been covered, the chamber 2 has ceased to be in communication with the chamber 10, and has re mained in communication only with atmosphere by the conduit 84 which the lifting of the valve 6 has opened. Consequently, for this short time, which is that during which there would be found a shortage of fuel, the output of fuel is increased by the increase of pressure created in the chamber 2 by this arrangement.

Figure 6 represents a variation of this arrang-ement. In this variation the hole 142 of the plug 139 is done away with. Holes 140 are bored in the surface of the piece 134 towards the lower part of this piece. Opposite these holes 140 the rod 137 is provided with flats which extend down to the lower part of this rod, so that the said lower part i placed in communication with the annular space 136, where there is a certain vacuum instead of being, as in the first arrangement, in communication with atmosphere. The rod 137 is thus, in this second arrangement, dawn less easily than in the former case, by the partial vacuum existing in the chamber 10, but the principle of the action is the same in the two cases.

The invention comprises, in addition, an arrangement consisting of a piston 21 connected with the valve 6 and havng approximately the same diameter. This piston 21 can slide in a cylinder 20, closed at its upper part and communicating freely by its lower part with the interior of the carburetor. This arrangement is characterized by a thread 131 made in the external cylindrical surface of the piston 21, while the inner cylindrical surface 1'' the cylinder 20 is smooth. The effect of this arrangement is extremely characteristic. The thread acts at first as would be the case with a number of circular grooves and opposes the direct passage of the air from one face of the piston 21 to the other, parallel to the axis of this piston, so that practically the air can only pass from one face of the piston to the other by following the helicoid of the thread, the small section of which is suitably chosen so that the lifting and falling movements of the valve may be as slow as desired. On the other hand, for a piston 21 having a diameter and a length of several centimeters, the length of the extended thread 131 amounts to several meters. The inertia of the air mov ing in this thread greatly reduces the supply of air passing from one face of the piston 21 to the other, when this passage of air takes place alternately in one direction and the other, and the changes of direction follow each other rapidly, as is the case for a carburetor applied to an internal combustion engine. Consequently, the thread 131 suppresses or greatly reduces the rapid oscillations of the piston 21 while permitting this piston to move sufficiently quickly under the action of a difference of pressure existing between these two faces when this difference does not change in direction.

The same result would be attained if the external surface of the piston 21 were smooth and if the inner surface of the cylinder 21 were provided with a thread, as is shown in Figure 7.

Another device of the invention consists in that the throttle valve 5 is mounted not on a single axis which passes entirely through the tube in which this valve is fitted, but on two cylindrical semi-axes 109, 110 (Figure l) situated in a line one with the other on each side of the valve 5, and the inner extremities of which, only penetrating for a short distance into the interior of the tube, each carry a longitudinal slot into which the valve is inserted very accurately and remains fixed by the elasticity. lVhen the valve is open, the extremities of the two semi-axes only obstruct very slightly the tube.

1. A carburetor including a casing ha'vling-a float chamber, and a mixing chamber, there being a fuel conduit leading from said float chamber; a fuel jet situated in the mixing chamber at the extremity of the :fuel conduit coming from the float chamber; a throttling valve for the carburetted air situated after the mixing chamber, an automatic vain e controlling the principal air inlet of the carbunetor; aconduit starting in the passage chamber (between the valve and the chamber), and opening into the upper part of the vfloat chamber above the level of the fuel, the said float chamber being air-tight to atmosphere; a conduit starting at atmosphone and terminating in the mixing chamher close to the extremity of the fuel jet, the axis of the extremity of the conduit and the axis of the jet being approximately perpendicular one to the other and arranged in such manner that a jet of air coming from the conduit strikes against the extremity of the jet nozzle; a conduit starting at atmosphere and opening into the upper part of the float cham- I ber above the level of the vfuel, and a throttle for this conduit, the said throttle being controlled by the automatic valve in such manner as to open when this valve lifts.

2. A carburetor including the combination, with a raising having a float chamber, a mixing chamber, there being a principal air inlet port, of an automatic valve controlling said air inlet port, a conduit associated with a passage chamber in said carburetor located between said valve and said mixing chamber and connecting said passage chamber with the upper part of said float chamber, and an automatic throttle capable of closing said conduit upon increase of asuction tained in the passagechamber over a predetermined degree oi: suction normally determined by the operation of aforesaid automatic valve.

3. A carburetor including the combination, with a casing having a principal air inlet port and an automatic valve controlling said air inlet port, a cylinder, one side of which is closed the other communicating tree- 1y with the inside of the carburetor, the innor cylindrical surface of said cylinder being smooth; a piston connected with the said valve, the said piston being located within said cylinder and provided on its exterior cylindrical surface with a helical groove extending several times around the said surface of the piston and forming a communicating passage between the faces of said piston.

it. A carburetor including the combination, with a casing having a principal air inlet port, a piston connected with the said valve, the outer cylindrical surface of said piston being smooth; a cylinder, one side of surface with a helical groove extending several times around the said surface of the cylinder and forming a communicating passage between the faces of said piston.

In testimony whereof I have signed this specification.

. PAUL LOUIS LEMOINE. 

